Natural gas and other types of fuels may include a liquid component therein. Such “wet” gases may have a significant liquid volume. In conventional compressors, liquid droplets in such wet gases may cause erosion or embrittlement of the impellers or other components. Moreover, rotor unbalance may result from such erosion. Specifically, the negative interaction between the liquid droplets and the compressor surfaces, such as the impellers, end walls, seals, and the like, may be significant. Erosion is known to be a function essentially of a combination of the relative velocity of the droplets during impact, droplet mass size, and impact angle. Erosion may lead to performance degradation, reduced compressor and component lifetime, and an overall increase in maintenance requirements.
Current wet gas compressors may use an upstream liquid-gas separator to separate the liquid droplets from the gas stream so as to limit or at least localize the impact of erosion and other damage caused by the liquid droplets. The equipment required for separation, however, generally requires additional power consumption. Another approach is to use a convergent-divergent nozzle such as a de Laval nozzle and the like so as to accelerate the gas flow to a supersonic velocity. The resulting supersonic shock may break up the liquid droplets. The supersonic shock, however, also may lead to a pressure drop upstream of the compressor and therefore an increase in overall compressor duty.
There is thus a desire for improved wet gas compression systems and methods of avoiding erosion. Preferably, such systems and methods may minimize the impact of erosion and other damage caused by large liquid droplets in a wet gas flow while avoiding or at least reducing the need for liquid-gas separators, supersonic shocks, and the like.